1. Field of the Invention
This invention relates to the field of chemistry. More particularly, this invention relates to dye lasers. Still more particularly, but without limitation thereto, this invention relates to dye lasers having extended operating lifetimes.
2. Description of the Prior Art
It is well known that complex organic dye molecules can be induced to emit coherent laser light. The active medium of a typical organic dye laser consists of a dilute solution of the organic material dissolved in a common solvent such as water or alcohol.
The term "dye" laser is derived from several classes of organic dye compounds in which lasing has been produced. However, a great number of compounds useful in dye lasers do not fit the general classification of organic dyes. A major advantage of the organic dye laser is its tunability. That is, the output of an individual laser can be changed continuously over a range of wavelengths. This feature makes the dye laser particularly suitable for use in isotope separation processes based on selective photoexcitation of a particular isotopic species, since the narrow bandwidth and exact wavelength requirements of the excitation source generally require that a finely tunable laser be used.
A major drawback of the prior art dye laser employing coumarin dyes as well as other dyes has been the failure of the dye solution to continue lasing after a short period of time due to degradation of the dye solution. In order to lengthen the effective lasing lifetime of the coumarin dyes, various techniques have been attempted in the prior art. They include: (1) to completely absorb the laser dye out of the dye solution; (2) to absorb the reaction intermediates out of the dye solution and slow down the dye degradation process; (3) to control the wavelength of excitation to which the dye is exposed; and (4) to use an inert gas rather than air as the cover gas over the dye solution. Optionally, some other methods would just change the dye and solvent to obtain the desired results.
The present invention provides a "clean" way to extend dye lifetimes, "clean" in the respect that the use of absorptive materials or additives would not be needed. These latter factors, as are commonly used in the prior art, can also contaminate, slow down, or markedly increase the complexity of the dye solution handling procedures.